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The growing human population requires vast amounts of supplies that are satisfied by a large agricultural expansion leading to alarming deforestation of tropical forests.Agriculture in the large part now is unsustainable as tropical soils are relatively nutrient poor, the amount of organic matter decreases fast and the soil invertebrates and microorganisms vanish over time. From a socio-economic point of view, agroforestry is a sustainable alternative to slash-and-burn practices, but its impact on termites, major macroinvertebrates responsible for the organic matter turnover, is poorly understood. Furthermore, other vegetation layers besides tree canopy are rarely included in studies despite their strong effect on soil macrofauna. Thus, we investigated the impact of human activities in Southern Cameroon by analysing the biomass of termites, the soil properties, the vegetation structure at three different classes (trees, shrubs and herbs) and the amount of raw vegetal material along a land-use gradient of primary forest -secondary forest -cocoa agroforestry -maize cropland.Within each of the habitats, two independent areas of 1 ha each were laid out for samples collection. Our results show similar trends for all variables, with a reduction of organic carbon as well as available micronutrients, plant diversity and abundance and dead plant matter stocks along the land-use intensification. The same trend is shown by the abundance and biomass of termites, best exemplified by the absence of soil-feeding termites in the maize cropland. We thus recommend for support to nature-friendly agroforestry systems preserving a large share of the original soil invertebrates.

Low molecular mass organic acids (LMMOA) are a part of the carbon cycle, and represent an important component of the active organic carbon in soil. The aim of this study was to determine the content, speciation and behavior of LMMOA in soils under Carpathian beech forest with different herb vegetation (herb poor, herb rich), and to assess the relationship between herb vegetation cover and LMMOA. We hypothesize, that LMMOA can infl uence herb vegetation richness through their (LMMOA) ability to release nutrients in forests soils. Speciation of LMMOA, nutrition content (PO43-, Ca2+, K+) and element composition in aqueous extracts were determined by means of ion chromatography and inductively coupled plasma – optical emission spectrometry (ICPOES) respectively. Sorption characteristics were determined in BaCl2 extracts by ICP-OES. Active, exchangeable pH and DOC (dissolved organic carbon) were also determined. Elemental composition of parent rocks was assessed by means of X-ray fluorescence spectroscopy. It was found that, on herb poor localities with higher LMMOA contents, the elements complexation and their further transport into the deeper parts of soil profile happens. There is also an increased dissolution of alumosilicates. And conversly, lowercontents of LMMOA were determined on herb rich locality, leading to nutrients mobilization but not to their leaching. The soil sorption complex is not enriched by Al3+ as there is not increased weathering of aluminosilicates. The result of this study is a diagram showing the influence of LMMOA on vegetation cover richness.